Wells its been a while since the last update, everything has been happening except rocket related activities unfortunately. So progress has been few and far between, heres a run down on whats been happening since Space Access.

Space Access

Once again a very fine conference held in Phoenix, Az, my thanks go out to Henry and everyone else who made it possible. It was good to catch up with friends from the previous year and meet new people, was good to meet Charles Pooley of Microlaunchers and with thanks to Charles for enabling us to speak at the conference.In my talk I covered my plans and approach to the N-Prize, notes and pictures of which can be found under the N-Prize link on this site. I mentioned using a stepped appraoch to achieving the prize, building upon proven concepts and ideas and implementing this all into the N-Prize vehicle, yes taking longer and potentially costing more in the long run but at least I will be 100% confident when the fuse is lit on the N-Prize launcher, knowing everything has been tried and tested in all aspects.

Sounding Rocket

With my stepped approach the first step is to build a reusable liquid fueled sounding rocket, acting as a platform for engine/component and flight testing. This first rocket which I have started work on will stand at 10ft tall and have a diameter of 8in, will be powered by a 300lbf thrust lox/kero engine, which will be of the same construction techniques that the upper stage N-Prize engines will have, the idea is to continually upgrade the rocket with systems that I plan to use, such as engine gimblaing, guidance and control etc. and then pass the electronics from this test bed right over to the N-Prize rocket knowing everything is in working order.

I hope you won’t take my feedback in anyway as been negative toward your project, but being a person who has some direct exposure to launch vehicle programs and involvement in space launch start ups. I think most people here are completely off target with their proposals for this competition. There seems to be a fairly universal theme here settling on building some kind of mini LOX powered rocket, that will somehow manage to do what no existing or proposed system based on LOX has achieved. And that is simple, reliable, low cost and responsive space launch operations. When I challenge most people on why they keep choosing this direction the common answer is "cost & availability", but any person with a background in real launch vehicle programs knows that propellant cost is a small fraction of total launch vehicle & operation cost.

I feel that much of this preoccupation with LOX comes from some deep underpinning that it is somehow a "real" rocket fuel, the one that big guys use. A real assessment of its merit & application to achievement of the goals of the N-prize would show it has to be the least attractive option, for realizing a truly low cost small scale rocket vehicle.

Among its core issues.

1/ Cryogenic temperature require either alloy or steel propellant tanks, which make it near impossible to achieve high propellant mass fractions. Or the use of expensive and yet to be fully qualified composite tanks for pressure feed vehicles, once again placing cost way outside of the N-prize budget. Not to mention extra order of ground operation complexity due to handling of cryogenic material. Plus pre-loading requirements such as cascading dry gas purges etc required to prevent formation of ice in lines and valves, and the inability to hold on pad for long periods if you have to scrub without dumping your LOX.

2/ Pressure feeding requires He - which is expensive, poor in density and requires high pressure (2000 to 3000psi ) containment. Once again more weight, or a composite cylinder - expensive.

4/ Boil off - you need between 2 to 3 times your flight load on hand to cater for boil off, thus your cheap oxidizer starts to look more expensive now.

5/ Reliable and stable ignition and combustion of LOX based motors takes a lot of work, and should not be underestimated. The effects are far from trivial as the size of motors scale beyond 1000lbs, and if pumps etc are incorporated the issues magnify.

On your site you mention building a pump feed 1st stage, have you investigated how much pumps made for reliable cryogenic service cost. And what’s involved in fabricating different types of pumps when LOX is the working fluid?. Again the pump project alone will most likely kill your project time and your budget.

In planning to make a mini version of what the "big guys" build you will simply inherent all the same issues they have, which require all of the exotic and expensive work a rounds that have created the current issue of high cost access too space.

I have no problem stating directly there is no way that a LOX powered expendable vehicle will ever win this prize, while sticking to the budget provisions. If you want my advice target either storable bi-prop or hybrid or solids.

If it where me I would look at something like this.

Propulsion (lower stage/ boosters)

Hybrid motor using 98% Nitric Acid & Sorbitol or Wax with Aluminum powder - all readily available, sortable and high in density impulse. Pressure feed by CO2 - high density moderate pressure, can be stored in alloy tube running the center of oxidizer tank. Thus forming a central stiffening element to which you can attach your thrust chamber.

Thrust vector control by either thrust vanes or LITVC using CO2 - would need to do trade study on this.

Upper Stages

Very low pressure Vapak type propulsion using Propane or Butane with Acid. The Acid could be held in a PVC bladder inside a the fuel tank negating all secondary feed system. And give good ISP (300+sec) in vacuum. Hand lay up 2 halves of a sphere out composite and bond them to make you tank.

Structures

You could make your propellant tanks by hand laying up glass or carbon fiber over PVC or ABS pipe, all off the shelf and easy. Your hybrid combustion chamber from thick cardboard tube, with cast fuel inside and composite over wrap. You could go for cast light weight refractory cements for your nozzles. Over wrapping of the chamber could be done using braided bi-axial composite sleeves and epoxy or phenolic laminating resins.

Stage Separation

Separation events are a large cause of failure modes in launch vehicle missions, keep them to a minimum. I have heard some people quoting up to 5 stages which increases the possibility of failure many fold, and is way to many this kind of project - I suggest you keep it below 4 and in fact 2 stage would be worth considering even if it means a bigger rocket.

Avionics

Here is the killer the most recent attempt that we have made in producing a "low cost" but accurate INS still cost more than this projects budget allows (>$1.5K). You will need to look at some form of very basic pointing system (horizon / magnetic) to get some control over your orbital insertion co-ordinates. I have strong doubts you will get issued with a permit for this project to place something in orbit if you cant give some reasonable assurance of your final orbital parameters. After all you might take somebody expensive space asset out.

As I have said I hope my post is not taken to be put down, as I would really like to see somebody actually take this prize out. But if we as enthusiast are going to make a quantum leap forward toward redefining space access the redundant ways of thinking need to over turned. And really believe that LOX is part of the old way of thinking, and as such won’t bring about the goal we are seeking.

Hybrid motors are the only motors to have actually killed anyone in the new space arena yet.

Nitric acid is a terrible thing to have to play with. It was also involved in the Nedelin accident, which as far as I am aware, the worst accident in rocketry ever.

You can autogenously pressurise LOX. You can also use the acceleration head on its own quite happily on upper stages.

You managed to include an alloy pipe in your booster anyway.

Steel pipe is cheap.

If you stay clear of hydrogen and helium most of the headaches with LOX disappear.

LOX condensers are cheap and don't count against budget.

"Big Boys" use storables and kill people. A lot. They all recommend against storables and solids due to handling difficulty, danger, pollution and wear on equipment.

The guys who built the shuttle say the things that held it back from ever being cheap were the uses of storables in the OMS Pods and RCS (which need thier own facility due to toxicity), hydrazine in the APU's (which catch fire) and hydrogen in the main engines which leaks all over the place.

They wish they had gone with LOX Methane the whole way through, for propulsion and RCS.

Oddly enough,Armadillo Aerospace, one of the smallest functional shops, has come to the same conclusion. They use LOX and Methane both autogenously pressurising.

I haven't seen any studies anywhere suggesting replacing LOX was a key to lowering prices or difficulty.

As the 'other' New Zealand N-Prize entry, I am avoiding all pumps partly to ensure we are playing with dis-similar techology. However I do believe the Kiwi 2 Space team is looking at pumps with very few moving parts.

Finally, cheap and reliable avionics should be one of the spin-offs of this prize. If you stick around you could participate in designiing such a system. There are a few threads around here on guidance.

Hybrid motors are the only motors to have actually killed anyone in the new space arena yet.

** I assume you refer to the Scaled accident here, which is a mild misrepresentation at best. The accident was completely due to poor handling practice of Nitrous Oxide, and not related to hybrid propulsion operation. Large scale LOX and gaseous oxygen have been involved in many more industrial and propulsion mishaps than probably all other propellants combined. And historical fatalities is not a robust method to argue the reliability and or operational merits of a given propellant. Fatalities occur because of "poor" and risky practice or basic human error, which allowed a failure to happen near personal. If we look at launch failures as whole and not just those that have killed you get a better picture of whats more reliable.

Nitric acid is a terrible thing to have to play with. It was also involved in the Nedelin accident, which as far as I am aware, the worst accident in rocketry ever.

** Concentrated Acid is an industrial commodity and is handled globally in the mega tonnes per annum, without a large volume of serious incidents. Following safe practice it is no more hazardous than LOX, which can kill you on contact or direct inhalation (freezing) just as easily as acid. Following safe practice for all energetics is a must, being fooled into thinking that any are benign is where the real trouble and deaths start. Accidents in the early days of spaceflight once again relate back to lack of knowledge with regard to safe practice, knowledge of compatible materials, and the poor quality (contamination) of early chemicals.

You can autogenously pressurise LOX. You can also use the acceleration head on its own quite happily on upper stages.

**Agreed - Vapak technology has some merit for upper stage application, but still wont scale down well to small rockets. Can I ask have you had direct experience in operations with LOX?. Verdict is out on how stable this technology is in flight, my understanding is that large unstable vaporization events in LOX tanks could contribute to POGO.

You managed to include an alloy pipe in your booster anyway.

**Yes but it was a smaller pressurant tank (commercial extrusion would do infact ) , not the whole propellant tank. Issues abound when trying to build a thin walled alloy tank for LOX, not to mention the thermal cycling (loading / dumping) issues which introduce additional stress. The poor bulk density of LOX, and requirement for a lot of ullage for boil off, means you will not achieve a decent mass fraction using alloy tanks and pressure feed. Unless you go for very low tank pressures, and then you get a poor performing fragile rocket with low density impulse. Or you need cryo ready composites which don't exist in the same sentence as "low cost"..A weight trade off study will quickly show it will be near impossible to get your mass fraction anywhere near 0.7 without composites, or other technologies that are out of the scope of this project. Thus requiring either many stage to reach your delta-v, which means more complexity due to more staging events. Or a much larger rocket, which means more cost.

Steel pipe is cheap.

**Yes but way too heavy..

If you stay clear of hydrogen and helium most of the headaches with LOX disappear.

**Not really - you will still need to pre-prep all of your contact surfaces to oxygen standard. Then you will need to insulate to reduce ice formation. Your valves will require lots of testing and higher actuation torques due to contraction at cyro temp, you will also need to heat trace any valves. Plus you will need to perform a series of cascading dry gas purges to remove any trapped moisture in your system. If this fail's ice shards can lock your ball valve, or tear your seals causing failures. Also if you are going to try and use very thin walled tanks you will need to get your tank pre-chill cycle timing right or you will risk structural failure, or imploding. Just ask Space X about when the Falcon tank buckled because they de-tanked to quickly. Also your ignition, start up and combustion stability issues come into play. Acid would give you very easy ignition and stable mixing and combustion with a hypergolic fuel, it would also store in a hand fabricated composite tank. And give you a density 1530kg/m3 as opposed to 1108 for LOX, thus shrinking your tank and upping your mass ratio. Hydrogen Peroxide will also allow very simple catalytic ignition, good bulk density and the ability to store in polymer (HDPE) lined tanks, but with some extra handling requirements.

If you a prepared to deal with one cryogenic then adding a second is of little consequence, as all of the same procedures & operational requirements just need to be doubled. Hydrogen just introduces a little more problems because of its rotten bulk density and far colder temperature, than Methane. Don't be fooled though because some experimenters have managed to build 1000lb thrust motors that seem to burn well on a test stand, they are all yet to build a high thrust to weight ratio launch vehicle qualified motor, that's flight proven. Only Space X has done this and once again with a budget past $100million of Elon's personal capital.

LOX condensers are cheap and don't count against budget.

**Okay so your intention is to produce your own LOX?. Hmm seems like an extra added complexity and cost, it also would tie you to a fixed facility which I think is going to be a big hurdle to achieving the N-prize.

"Big Boys" use storables and kill people. A lot. They all recommend against storables and solids due to handling difficulty, danger, pollution and wear on equipment.

**Big boys have fixed launch infrastructure with massive investment in LOX storage & loading, and have thus tied their vehicles to these legacy sites. Try getting your gas company to slide up and decant their LOX directly into your rocket?. Or better yet let you dump your LOX back into their tanker when you have an abort... Now you will require a very large & expensive portable dewier to get your LOX to the launch site, what if you decide you want to launch from a remote and difficult to access site?. I am also keen where you get this assertion that storables have killed lots of people from?.

Aranespace operated the Ariane 4 launch vehicle on storables for many years and greatly reduced cost of operations over their American counter parts, so much so the US launch industry required government subsidies to compete. India's PSLV & GSLV both use solids & storables, as does all of the Russian launch vehicle fleet bar Soyuz. All with impeccable reliability records, as too do all of Orbital Sciences launch vehicles which are solids.

The guys who built the shuttle say the things that held it back from ever being cheap were the uses of storables in the OMS Pods and RCS (which need thier own facility due to toxicity), hydrazine in the APU's (which catch fire) and hydrogen in the main engines which leaks all over the place.

**You are referring to Nitrogen Tetroxide, Hydrazine & UDMH all of which are known carcinogenics. I would be referring to either Nitric Acid (WFNA type) & Hydrogen Peroxide. With Nitric Acid you could use Turpentine and get a hypergolic combination. You can buy Turpentine at your local hardware store in plastic bottles, not any more hazardous than Kerosene.

**The shuttle has many issues that far out weight the use of hypergolics in the OMS, and I might add it was excessive ice build up and external tank issues that has contributed to its failures.

They wish they had gone with LOX Methane the whole way through, for propulsion and RCS.

**They say this now, because Methane (LNG) is in vouge. Just 10 years ago its was considered to be a very hazardous gas, and was involved in one the largest industrial accidents in history back in the 60's. Only today with significant and costly advances in storage and transportation systems is LNG gaining acceptance as an energy source. All you get here is another cryogenic which once again introduces more system level complexity, both in preparation and operation. The Japanese galaxy program has run into huge cost over runs and delays due to their choice of this propellant, and Aeries is also well behind schedule and running way over cost due to dependency on these same technologies.

**Also there is no point in applying the methodologies or way of thinking of major aero's who build multi-billion dollar government funded space vehicles. You are a enthusiast team trying to build a remarkably low-cost vehicle to do the same job on a much smaller scale, so the paradigms need to be worlds apart. You need to start thinking in more "clandestine" terms, based on what materials; manufacturing techniques capabilities are actually applicable within this very small budget. Rather than picking LOX because you think its safe, cheap or readily available, and then trying to engineer around this choice.

Oddly enough,Armadillo Aerospace, one of the smallest functional shops, has come to the same conclusion. They use LOX and Methane both autogenously pressurising.

**They went this way because they got blocked going in their original direction which was Peroxide, and they only changed because their 90% Peroxide supplier shut shop. They made far more rapid progress when they used Peroxide graduating to a full scale X-prize test vehicle in under 2 years. And I might ad they also suffered a hard start on their LOX vehicle at the x-cup, which is a pretty common event unless you know how to run your start up sequence properly. Also keep in mind they have spent millions of John Carmack’s $$$ on this work, even though it’s a small shop.

**I was involved in the construction of Ausroc 2 rocket in the late 80's which to date is the largest non-governmental rocket of its type (LOX) built pretty much anywhere, it was no where near large enough to win this competition. And we estimated its cost in manufacture/ materials to be over $120,000AUD, which is well beyond the budget set forward for N-prize. All of the technical issues in this program came form trying to apply LOX to an enthusiast built rocket vehicle, using off-the-shelf hardware adapted for LOX service. I would urge you not to repeat the same process if you want to make a serious attempt at a very cheap rocket.

I haven't seen any studies anywhere suggesting replacing LOX was a key to lowering prices or difficulty.

**How long have you been involved in the space transportation field? There is only dozens of operational & historical examples of small launch vehicles with lower cost, and more responsive operations than cryogenic launch options. Personally I have contributed to around 13 or so launch vehicle trade studies, both in co-operation with governments and major aerospace. This includes work with AMROC (Aquilla). Orbital Science Corp (Pegasus), Atlantic Research (now ATK), British Aerospace (Skylark Sounding Rocket/ Australian Launch Vehicle/ Southern Launch Vehicle) and others. These have covered the gammit of liquid, solid & hybrid propulsion systems of which all have merit, but have to be assessed based on the system goal they are being applied too. I must point out here again that looking at BIG rockets and thinking the same scale of economy will apply to your project is extremely floored. A large launch system can easily absorb the additional cost associated with complexed operational procedures, and expensive pad infrastructure. All cost which do not scale in accordance with launch vehicle size, which is why more small launch designers target solid propellant or hybrid. And also behind the growing resurgence of interest in Peroxide, now that its storage & handling is better understood. Peroxide & NItrous Oxide are under heavy investigation as ideal candidates to replace the mentioned toxic storables, as "green" propellants.

As the 'other' New Zealand N-Prize entry, I am avoiding all pumps partly to ensure we are playing with dis-similar technology. However I do believe the Kiwi 2 Space team is looking at pumps with very few moving parts.

**I wish them luck here - Pumping super critical fluids such as LOX is a science in itself, not to mention the additional requirements of making high speed bearings, shaft seals etc all work at LOX temperature.

Finally, cheap and reliable avionics should be one of the spin-offs of this prize. If you stick around you could participate in designing such a system. There are a few threads around here on guidance.[/quote]

**Here is an area where a lot of advancement can happen for sure. I do not design electronics; my specialty is propulsion and launch vehicle architectures. In conducting my work here in Australia I offer the chance for engineering students to develop avionics packages, but the key goal has been a full blow strap down INS rather than a basic pointing package. Perhaps I will propose one for the 2010 project round?.

There are a lot of Methane Propane and Ethanol designs from the 60s 70s 80 and 90s. Then they were ways to keep your ISP high while avoiding the ever leaky Hydrogen. The new fad is more to build something that can be easily refueled on Mars.

Vapour Pressure Pogo can be controlled by heat exchangers, regulators and the accumulators that will be in there anyway, but you still get water hammer all over the place.

However that's all too expensive and complicated for the N-Prize so I am working on some mechanically simple ways to even out the vapourisation process. It doesn't have to be great, it just has to stop the engine from flaming out or exploding. But you are correct that it is a design driver.

There are a lot of Methane Propane and Ethanol designs from the 60s 70s 80 and 90s. Then they were ways to keep your ISP high while avoiding the ever leaky Hydrogen. The new fad is more to build something that can be easily refueled on Mars.

**Add to the list Propylene (denser and better performing than Methane). You might want to check it out...

Vapour Pressure Pogo can be controlled by heat exchangers, regulators and the accumulators that will be in there anyway, but you still get water hammer all over the place.

**Kind of but the real issue is the liquid becoming saturated with vapor as its boiling, cant stop that from entering into your feed lines. The issue grows as you get closer to the end of your liquid run, leading to thrust oscillation which in turn shake up the LOX leading to more vapour. If you can find a way to tune it out in your motor you should be okay.

However that's all too expensive and complicated for the N-Prize so I am working on some mechanically simple ways to even out the vapourisation process. It doesn't have to be great, it just has to stop the engine from flaming out or exploding. But you are correct that it is a design driver.

**Some form of heat exchanger that uses heat from your motor to warm some of the LOX and pipe it back to the tank might help you here. The vapak process is tied the enthalpy of your liquid, as it boils (expands) it is slightly cooled thus dropping the temperature at the surface of the liquid. If you can top the cycle up with some warm gas you would have at shot at interrupting the cooling cycle, and keeping the pressure oscillations down.

I think you will love my rocket design, its pretty novel

** I look forward to checking out, and as I said if you need some pointers on using LOX and the issues that come up feel free to mail me.

What about using a solid oxidiser, such as SO3, with Propane? The SO3 would be lining the inside of the combustion chamber, much in the same way as the fuel does in a Hybrid rocket, and the Propane would be pressure fed. Basically an inverse Hybrid. It's simple, but sould be able to achieve better Isp than a solid rocket on it's own, plus it's a lot easier to throttle. What other oxidisers could be used?

What about using a solid oxidiser, such as SO3, with Propane? The SO3 would be lining the inside of the combustion chamber, much in the same way as the fuel does in a Hybrid rocket, and the Propane would be pressure fed. Basically an inverse Hybrid. It's simple, but sould be able to achieve better Isp than a solid rocket on it's own, plus it's a lot easier to throttle. What other oxidisers could be used?

Hmm there hasn't been much work done on inverse hybrids as yet. I have found reference to couple of European Patents.. One is EP0727403 which describes inverse hybrid motor using mixtures of Ammonium Perchlorate & Potassium Perchlorate with Hydrazine (Yuk).

I would be pretty confident that most solid oxydisers would enhance the possibility of a detonation, as most are capable of forming explosive compounds with minimal extra reactants involved. You would also loose your 0 TNT equivalence rating if you use a solid oxidizer such as Ammonium Nitrate, and would still require a binder to hold your oxydizer grain together. In effect you would have a fuel boosted, oxydiser rich solid propellant motor more than hybrid.

What other options are there for liquid oxidisers other than HNO3, N2O4, LOX, and H2O2? Anything that is easy to get hold of and relatively safe to handle?

None really - Nitrous Oxide (NOX) is about the only one that fits your criteria of easy to get a hold of and relatively safe to handle. But it is compressed gas and must still be handled with respect, and requires high pressure containment. There is some issues with NOX vapor being susceptible to detonation with minimal energy input, but liquid is quite stable. The problem can be fixed by charging the NOX tank ullage space with an inert gas such as He or O2.

In H2O2 defense it has copped a very bad wrap in the past due mainly to the poor handling techniques practiced back in WW2 days. Not only that but the Peroxide back then was a very contaminated product. These days the paper pulp industry go through mega tonnes of 70% strength Peroxide without major issues, because the handling procedures are well known. With a little bit of research you can very easily obtain 35% or 50% food grades and concentrate them into 85%, via fractional distillation. And there are also several small ventures set up to supply rocket grade Peroxide to experimenters, such as Peroxide Propulsion in Sweden. Developments in new ceramic catalyst and consumable catalyst means you can now used highly stabilized Peroxide, without the issues encountered by the old silver cat beds being poisoned.

In terms of bulk density & performance the stuff cant be beat, not only that but it decomposes to oxygen & steam which is very environmentally friendly. And it will store in polymers such as HDPE, U-PVC and PVDF which makes it possible to start using commercial off the shelf composite tanks. Such as those made for the water treatment, filtration/ softening industries.

All you have to do is read up and make sure you handle the material with its due respect. Which is true of all energetic materials, and should never be forgotten if you value your health

But does it fit the criteria of being easy to get hold of? I recall Armadillo Aerospace were planning on using it, until their supplier shut. For test vehicles that shouldn't be so much of a problem, right?

I think they were trying to use 98% peroxide, which is difficult to find, but if you instead buy 50% you can distill it to the high concentrations needed for a decent rocket without too much trouble, though I imagine if it were really that easy armadillo would have just done it themselves.

But does it fit the criteria of being easy to get hold of? I recall Armadillo Aerospace were planning on using it, until their supplier shut. For test vehicles that shouldn't be so much of a problem, right?

Armadillo made what I believe was a couple of bad choices. And I could be wrong here but there seems to be no mention anywhere of an attempt to secure or build their own concentrator. Something that can be done in quite a transportable setup, and would allow for point of use generation of propulsion grade peroxide. Thus negating the transportation issues, and the dependence on suppliers such as FMC who will only supply government.

The direction of trying to go toward the mixed mono-propellant although looking promising required significant work on catalyst bed development, as its no small feat to get a 50% solution to liberate enough heat to maintain decomposition temperatures. And for whatever reason I am unsure of John and team decided that bi-propellant design using a 70% Peroxide was too complicated?.

I would be pretty sure the amount they spent on developing the lox propulsion would have more than covered such a concentrating system. And would have given them some independence, instead of being at the mercy of large suppliers who don't want to support New Space efforts out fear of liability suits. There lox / methane work is generating some work though, but I don't believe that tying yourself to government contracts is the way to go. Really at the end of the day there is quite a few new space companies that are developing this technology, which just means that the government can play them off against each other for cost. Armadillo had a fairly unique program which I believe would have created the kind of "large cost reductions" we need to revolutionize space transportation.

On distillation, its not to hard at all. Small quantities to 85% can be done in lab beakers at a temperature of around 65deg C, but no higher than 75deg which is where explosive vapors can form. Larger quantity and or up to 90% will require distillation under vacuum of around 100mmhg. But you must be sure to use only class 1 materials for Peroxide contact, and passivate all contact surfaces. Grades higher than 90% are much more difficult and require fractional crystallization.

Some web surfing will provide lots of papers with good info on how to store & handle high test Peroxide.